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Provided by the Cornell Feline Health Center, Cornell University
What is diabetes mellitus?
Diabetes mellitus-also known as "sugar" diabetes-is a complex but common disease in which a
cat's body either doesn't produce or doesn't properly use insulin. During digestion, the fats,
carbohydrates, and proteins that are consumed in the diet are broken down into smaller
components that can be utilized by cells in the body. One component is glucose, a fuel that
provides the energy needed to sustain life.
Insulin is a hormone produced in the pancreas, is responsible for regulating the flow of glucose
from the bloodstream into the cells of the body. When insulin is deficient or ineffective, the cat's
body starts breaking down fat and protein stores to use as alternative energy sources. As a
result, the cat eats more yet loses weight. Additionally, the cat develops high levels of sugar in
the bloodstream, which is eliminated in the urine. In turn, sugar in the urine leads to excessive
urination and thirst. Cat owners often notice these four classical signs of diabetes mellitus:
ravenous appetite, weight loss, increased urination, and increased water consumption.
Diabetes mellitus is generally divided into two different types in cats: insulin-dependent diabetes
mellitus (IDDM)], and non-insulin-dependent diabetes mellitus (NIDDM)]. Approximately one-half
to three-quarters of diabetic cats have and thus require insulin injections as soon as the disease
is diagnosed. The rest have NIDDM; however, most ultimately require insulin injections to control
their disease.
While diabetes mellitus can affect any cat, it most often occurs in older, obese cats. Male cats are
more commonly afflicted than females. The exact cause of the disease in cats is not known,
although obesity (the major predisposing condition), chronic pancreatitis, other hormonal
diseases (e.g., hyperthyroidism, Cushing's disease, and acromegaly), and certain medications
(e.g., megestrol acetate and corticosteroids like prednisolone) have all been linked to the disease.
Burmese cats in New Zealand, Australia, and the United Kingdom are prone to developing to
diabetes, but this doesn't appear to be the case in North America.
How is diabetes diagnosed?
Diabetes mellitus is diagnosed based on the cat's signs, physical examination findings, laboratory
test results, and the persistent presence of abnormally high levels of sugar in the blood and urine.
Once diabetes has been diagnosed, immediate treatment is necessary.
Left untreated, diabetes will shorten a cat's lifespan. A dangerous, sometimes fatal condition
called ketoacidosis may develop, indicated by loss of appetite, vomiting, diarrhea, lethargy,
weakness, dehydration, and breathing abnormalities. Additionally, diabetes can lead to an
unhealthy skin and coat, liver disease, and secondary bacterial infections. A diabetes-related
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disorder called diabetic neuropathy may cause cats to become progressively weaker, especially
in the hind legs, impairing their ability to jump and causing them to walk with their hocks touching
the ground.
Diabetes treatment is based on the severity of the disease. Cats with ketoacidosis require prompt
intensive care, which usually includes fluid therapy and short-acting insulin injections. For cats
that are not severely ill, your veterinarian may recommend a treatment plan that includes insulin
injections or oral medications, along with dietary changes.
What is involved in treating a diabetic cat at home?
Each diabetic cat is an individual, and each responds differently to treatment. Some diabetic cats
are easy to regulate; others are not. Some can be treated with oral medications, while others
require insulin injections. Some cats' diabetes is transient-reversing course with the passage of
time-while others will require treatment for the remainder of their lives. Different cats respond best
to different types of insulin. Regardless of this variability, all diabetic cats do best with consistent
medication, consistent feeding, and a stable, stress-free lifestyle.
Insulin
Most diabetic cats require insulin injections administered under their skin twice daily. The
injections can be given at home, preferably at the same time each day. Your veterinarian will
show you how to give these injections, which are not painful-in fact, most cats are unaware that
the injection is being given. Because each is different, the proper type of insulin, dose, and
frequency of administration needs to be determined by your veterinarian. Ideally, this is based on
an 18- to 24-hour blood glucose profile, obtained through a veterinarian-administered insulin
injection and subsequent testing of blood sugar levels at regular intervals throughout the day.
Insulin dosage may change with time and may need to be adjusted based on new blood glucose
profiles, the results of intermittent blood tests and urine sugar measurements, and the cat's
response to therapy.
Oral Hypoglycemic Medications
Healthy diabetic cats can sometimes be successfully treated with glipizide, an orally administered
hypoglycemic medication that lowers blood glucose. Adverse side effects, although uncommon,
include vomiting, loss of appetite, and liver damage. If you use glipizide, have your cat's glucose
levels checked regularly to verify medication's efficacy. Although glipizide works for some diabetic
cats, most require insulin injections to successfully control their disease. In addition, the
administration of oral medication on a long-term basis is difficult for many cats and their owners;
insulin injections may be a better choice for them.
Diet
In addition to medication, an important step in treating diabetes is to alter your cat's diet. Obesity
is a major factor in insulin sensitivity, so if your cat is overweight, you will need to help him lose
weight gradually. Your veterinarian can tailor a safe weight-loss program, in which your cat loses
weight gradually. A high-fiber, high-complex carbohydrate diet not only can achieve weight loss if
necessary, but is believed to help control blood sugar levels after eating. (Underweight cats
should initially be fed a high calorie diet until they reach their ideal body weight.) Other diabetic
cats respond well to carbohydrate-restricted diets. Although diabetic cats have been successfully
managed with both types of diets, some cats respond better to high-fiber diets and others to lowcarbohydrate diets. Trial and error can help determine the best diet for your cat.
Your cat's feeding routine is also important. While many cats are "free-choice" feeders (i.e., food
is left out for them to eat whenever they want), this may not be the ideal routine for a diabetic cat.
Ideally, a cat receiving insulin should be fed half its daily food requirement at the time of each
injection, with the unconsumed remainder available throughout the day. The timing of feedings is
less critical for cats receiving glipizide; nevertheless, food intake should be closely monitored.
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What are the potential complications of treating a diabetic cat?
Hypoglycemia-low blood sugar-is a potentially dangerous complication, usually caused by a
relative overdose of insulin. Hypoglycemia signs include weakness, listlessness, lack of
coordination, convulsions, and coma. Left untreated, hypoglycemia can be fatal. If hypoglycemia
develops, the cat should immediately be offered its normal food. If the cat is unable to eat, rub
some corn syrup onto the gums or, if the cat can swallow, slowly administer it by syringe into the
mouth. Never force fingers, food, or fluids into the mouth of a convulsing or comatose cat.
Contact your veterinarian immediately for further instructions if your cat exhibits signs of
hypoglycemia.
How do I monitor my diabetic pet?
Monitoring your diabetic cat is a joint effort between you and your veterinarian. Because your
cat's insulin requirements may change over time, periodic checking of blood glucose or serum
fructosamine levels is essential. Seek veterinary treatment at the first reappearance of
diabetes signs (increased thirst, increased weight loss, increased appetite, or increased
urination).
Some cat owners are willing and able to take on the task of measuring their cat's blood glucose
levels at home rather than in a veterinary hospital-a potentially less expensive and more accurate
monitoring method. Ask your veterinarian whether home glucose testing might be suitable for you
and your cat. More information can be found online at www.sugarcats.net/sites/harry/bgtest.htm.
At home, you'll need to be constantly aware of your cat's appetite, weight, water consumption,
and urine output. It is important to feed a consistent amount and type of food at the same times
each day, so that you can be aware of days that your cat either does not eat or is unusually
hungry after the feeding. Additionally, since water consumption is highly variable from one cat to
another, monitoring your cat's water consumption for a few weeks will allow you to establish what
is normal for your cat. Urine output can be roughly estimated by determining the amount of litter
that is scooped out of the litter box. This is less accurate if more than one cat uses the litter box,
but changes can still be meaningful. Any significant variation in your cat's food intake, weight,
water intake, or urine output can be a sign that the diabetes is recurring and immediate veterinary
care is needed.
What is the prognosis for a diabetic cat?
There is no cure for diabetes mellitus. However, some diabetic cats may lose the need for insulin,
months or years after diagnosis. If diabetes has resulted from obesity, it is likely to improve a
great deal-or even completely resolve-once the cat's weight is under control. If obesity or some
other disorder is not a factor, the diabetes probably will not go away; however, it can be
successfully managed. The serious chronic complications that afflict people with diabetes mellitus
(such as kidney disease, blood vessel disease, and coronary artery disease) are uncommon in
diabetic cats. Once control is attained with proper treatment and home care, a diabetic cat can
live many healthy years. Nonetheless, successfully managing a diabetic cat requires much
dedication and communication between you and your veterinarian.